A control apparatus and a method for the self-compensation of disturbance signals of a sensor are known from US 2003/0178989 A1, by way of example, wherein the sensor is a Hall sensor. The control apparatus disclosed therein has a comparison arrangement arranged in a control loop, and also an evaluation device connected downstream of the comparison arrangement, which evaluation device converts output values of the comparison arrangement into result values. The result values are fed to a correction device, which generates correction values, the correction values and also input values of the control loop being fed to the comparison arrangement and the input values being corrected by the correction values. The control apparatus can be operated independently of an operating mode of a sensor.
The disturbance signal is an offset that is assumed to be constant. Although the offset is largely eliminated by the control apparatus, a non-negligible inaccuracy remains in the ratio of disturbance signal to useful signal. A further disadvantage is that the control apparatus cannot be used, or can only be used to a limited extent, in the case of temporally variable disturbance signals.
Known methods for the compensation of disturbance signals, in particular offsets, comprise calibration cycles, adjustment of a signal and compensation of a drift of a disturbance signal by means of high-pass filtering. These techniques cannot be used for some applications, because e.g. it is not possible to carry out calibration cycles or because the input signal may be constant over long times, so that a high-pass filter may cause errors.